Knee cushion



FIG. 1 is a top perspective view of a knee cushion showing my new design;

FIG. 2 is a front side view thereof;

The rear side is a mirror image of the front side;

FIG. 3 is a bottom view thereof; and,

FIG. 4 is a right side view thereof.

The left side is a mirror image of the right side. 

The ornamental design for a knee cushion, as shown and described. 